The interferons (IFNs) are a multi-functional group of cytokines that participate in the implantation of the early embryo, maintenance of a successful pregnancy, initiation of innate immunity and regulation of adaptive immune responses. A recent gene inventory of the pig genome identified 39 type I, 1 type II and 2 type III IFN genes. The biological significance of a large number of genes from the same family suggests that IFN expression is developmentally regulated, including the up-regulated expression of specific classes, subclasses and subtypes during viral infection of the fetus. The purpose of the proposed project is to profile the expression of IFN genes in their receptors in healthy and virus-infected fetuses. The model system incorporates the natural infection of the late-gestation pig fetus with an arterivirus, porcine reproductive and respiratory syndrome virus (PRRSV). Aim 1 is to characterize the expression of IFN classes, subclasses and subtypes in the immunocompetent pig fetus. The hypothesis being tested is that specific IFN genes are preferentially expressed in the late gestation fetus and the pattern of gene expression is tissue specific. Under this aim, a real-time RT-PCR array is used to measure the expression of the individual porcine IFNs and their receptors. Expression will be measured in fetal, interface (placenta) and maternal compartments at 75, 85, 92, 100 and 110 days of the 114 day gestation period. Aim 2 is to measure alterations in fetal IFN gene expression during virus infection. Natural infection of the pregnant porcine dam with PRRSV at 85 to 90 days gestation leads to fetal infection. Two isolates that possess two different endpoints are used for infection. IFN and IFN receptor expression will be measured at 112 days of gestation. The pattern of gene expression will be correlated with viremia and PRRSV-specific antibody. The results will identify candidate IFNs that are involved in protecting the fetus or may be involved in fetal rejection. Aim 3 is the participation of pre-veterinary (prevet) undergraduate students into research. The experiential learning activities will teach undergraduate students research skills related to the development and use of a comparative animal model and basic molecular laboratory techniques. PRRSV infection of the late-gestation fetus provides a relevant model system for dissecting the interaction between a virus and its natural host. Another important innovation is the analysis of IFN gene expression in the immunocompetent fetus, which will provide an important comparative model for studies of human fetal infections, their consequences and potential therapies. PUBLIC HEALTH RELEVANCE: This project is the first-of-its-kind analysis of IFN and IFN-gene expression in the immunocompetent pig fetus. The model provides the means to test therapies and other treatments on fetal immunity and identify expression patterns involved in defense and pathogenesis.